The overall objective of the proposed research is to characterize the molecular events that establish cell differentiation during spore formation in Bacillus subtilis. Bacterial spores are highly resistant to many common sterilization techniques and often are implicated in food-borne illness. Understanding the process of sporulation should allow for the development of new, more effective sterilization techniques. The proposed experiments are conceptually based on a model where the developmental pathway leading to spore formation is established, in part, by the asymmetric distribution of integral membrane proteins across the sporulation septum. This model will be tested by methods designed to determine both the distribution of proteins across the septum, and the mechanisms by which these proteins are restricted to one or the other cell following division. These methods are broadly applicable to the study of other disciplines and therefore, should contribute generally to science and ultimately to human health.